Brad Pitt, Angelina Jolie and Britney Spears are subjects of a virus scam that is attempting to recruit computers for a denial-of-service attack on Microsoft.

Hackers have released a self-spreading worm, called Ahker-F, that promises pornographic movie clips of the celebrities. The emails contain text such as: "Watch Angelina Jolie and Brad Pitt cought [sic] on TAPE! SEXY CLIP! WATCH IT!"

However, the emails contain a .zip file that contains the worm. If opened, the worm spreads to the users email contacts, disables security settings on PCs and launches a denial-of-service attack against Microsoft's security update Web site.

"People's appetite for salacious gossip is insatiable, and some may be tempted to run what appear to be pornographic movie files distributed across the Internet," said Sophos. "However, virus writers have a long history of disguising their malicious code as this kind of content. Everyone should be very careful about what they choose to run on their computer."

The worm also spreads via file-sharing networks using filenames such as PORNO.exe, XXX.exe and Naked Britney.exe.

Sophos said only a small number of reports of the worm had been received by Thursday lunchtime.